Air cooled furnace and method of operating the same



Aug. 18, 1931. D. s. JACOBUS 1,319,174

AIR CQOLED FURNACE AND METHOD OF OPERATING THE SAME Original Filed June 17, 1925 INVENTOR ATTOR E YS Patented Aug. 18, 1931- STATES PATENT OFFICE DAVID S JACOIBU S, OF JERSEY CITY, NEW JERSEY, ASSIGNOR, BY MESNE ASSIGN- MENTS, TO FULLER LEHIGH COMPANY, A CORPORATION OF DELAWARE AIR COOLED FURNACE AND METHOD OF OPERATING THE SAME Application filed June 17, 1925, Serial No. 37,341. Renewed January 13, 1931.

My present invention relates to furnaces, and particularly those in which high furnace temperatures are used and in which the walls are cooled by air.

My invention will be best understood from the following description and the annexed drawing, in which the figure shows a vertical longitudinal section of a steam boiler and its furnace embodying one form 10 of my invention and with which my novel method may be practiced.

In the illustrative embodiment, the furnace chamber 10 is made up as usual of approximately vertically disposed walls ar- 55 ranged to provide a furnace chamber substantially rectangular in cross-section. A roof 11 has one or more powdered fuel burners 12 extending therethrough, the fuel being projected downward and the burning gases turning upward to the gas exit at the right of the chamber in the figure.- Over the furnace gas'exit is a water tube steam boiler of a typical form from which, after the gases have passed back and forth across 55 the water tubes, the gases leave through the gas exit 13.

The front furnace wall 14 is provided with a plurality of air passages 15 leading from vertically disposed air passages 16 d1- rectly into the furnace chamber adjacent the downcoming fuel. Beneath bottom 17 is an air passage or passages 18 receiving air from a duct 19, the passage 18,

communicating with the lower part of the passage or passages 16.

The side and rear walls of the furnace chamber are made up in sections, in the illustrative embodiment, each section being provided with a plurality of horizontal air passages 20 leading from the rear wall through the side walls to the air passage 16. The particular construction of the sectional furnace wall is no part of my present invcntion, but is more fully described in my copcuding application Serial No. 42,367 filed July 51 i925 and-further description thereof wili. therefore, not be necessary, it being understood that these horizontally disposed air passages may be formed in any desired manner.

the furnace Each of the horizontal passages .20 connects through the rear wall with a duct 21, each of which, in turn, connects with a duct 19.

The gases from the flue "13 pass throu h an air heater and from thence to a smo e outlet 22. The air heater is made up of a first part 23 and a second part 24, the air to be heated being forced b the fan 25 through the duct 26 into the ower part of the air heater 24 and, after passin back communicating with each of the powdered fuel burners 12.

With the arrangement described, air is forced by the fan 25 through the heater 24 and some of such air passes through the duct 19 into the horizontal ducts 20, this air cooling the side and rear walls of the furnace chamber 10 and, of course, becoming heated thereby, so that when it enters the passage 16 it will be relatively hot. Some of the air from the duct 19 will flow directlyinto the passage 16 through thevduct 18 beneath thefurnace wall 17 Some of the air from the heater 24 will pass to the fan 29, and from thence will be forced through the first air heater 23 and from thence to the burners 12. It will be seen that the air supply to the burner will be highly heated because such air has passed through the entire air heater, whereas the part which is supplied to the duct 19 passes through only a part of the air heater and that the coolest portion of such air heater.

While the air supplied to the ignited powdered fuel stream through the air passages 15 will receive additional heat from the furnace walls, I preferably operate the furnace so that the air supplied to the burners 12 through the duct 33 will be hotter than the air through the passages 15.

In the illustrative embodiment, the fur nace chamber is provided with the usual slag screen connected to the water circulation of the boiler, but since this is no part of my present invention, further description thereof will be unnecessary.

It will be understood that the embodiment of my invention may be widely varied and that some of the parts of my invention may be used independently of other' arts. It will also be understood that each 0 the air ducts may' be supplied with dampers, if desired, to control the amount of air flowing through the several passa es. It will also be understood that while have shown my invention applied to a powdered fuel furnace, some of its features may be used with other forms of fuel. The fan 29 may be omitted, if desired, but I prefer to use such a fan so that air deliveredto the burners can be undeixhigher pressure than the air in the duct 19 and by placing the fan 29 in the position shown, the -air handled by it is at a lower temperature and, therefore, of less volume than it would be if the fan were in the duct 32.

I claim:-

1, A furnace chamber having cooling air passages in the walls thereof. and communicating with said chamber, a fuel burner to supply fuel to said chamber, a first and a second air heater contacted in the order named by the furnace gases, ducts to lead heated air from the second air heater to said cooling air passages, and ducts to lead heated air from said second air heater to the first air heater and from thence to said burner.

2. A furnace chamber having cooling air passages in the walls thereofand communicating with said chamber, a fuel burner to supply fuel to said chamber, a first and a second air heater contacted in the order named by the furnace gases, ducts 'to lead heated air from the second air heater to said cooling air passages, ducts to lead heated air from said second air heater to the first air heater and from thence to said burner, and a damper to a control the flow ofair from the second air heater to the first air heater.

3. A furnace chamber having cooling air passages in the walls thereof and communicating with said chamber, a steam boiler contacted by the gases from the furnace, a first and a second air heater in the boiler waste gas flue and contacted successively by the waste gases in the order named, a fuel burner for said furnace chamber, a duct to lead heated air from said first air heater to said burner, and a duct to lead heated air fromsaid second air heater to said passages. 1

4. A furnace chamber having cooling air passages in the walls thereof and communicating with said chamber, a steam boiler contacted by the gases from the furnace, a'

first and a second air heater in the boiler .waste gas flue and contacted successively by passages in the walls thereof and communieating with said chamber, a steam boiler contacted by the gases from the furnace, a

first and a second. air heater in the boiler waste gas flue and contacted successively by the waste gases in the order named, a fuel burner for said furnace chamber, ducts to leadheated air from said second air heater to said first air heater and from said first air heater to said burner, a fan in said ducts between the first and the second air heaters, and a duct to lead heated air from said second air heater to said passages.

6. The method of operating a furnace which comprises projecting into the furnace a stream of fueLigniting and burning said fuel' in the furnace, extracting heat from the waste gases and heating air therewith, supplying said heated air to the fuel adjacent its place of ignition, extracting some of the remaining heat from the waste gases and heating air therewith, and supplying said last named air to the furnace where the fuel is burning.

7. The method of operating a furnace which comprises projecting a stream of fuel into the furnace, igniting and burning the fuel therein, extracting heat from the waste gases and heat-ing'air therewith, mixing said air with the fuel as it is projected into the furnace, extracting some of the remaining heat'from the waste gases and heating air therewith, and directing said last named air into the furnace adjacent the stream of burning fuel.

8 The method of operating a furnace which comprises projecting a stream of fuel into the furnace, igniting and burning the fuel/therein, extracting heat from the waste gases and heating air therewith, mixing said air with the fuel as it is projected into the furnace, extracting some of the remaining heat from the waste gases and heating air therewith, directing said last named air into the furnace adjacent the stream of burning fuel, and at a plurality of places spaced along the length of said stream.

- DAVID S. JACOBUS.

Ill 

